System for reducing injury from pinch zones in adjustable height work surface assemblies

ABSTRACT

Embodiments of a system for reducing injury from pinch zones in adjustable-height work surface assemblies are shown, the system including a desk surface; one or more adjustable-height legs, a controller for the adjustable-height legs; a Hall-effect sensor providing a signal to the system corresponding to a current draw of a motor in the adjustable height leg and wherein the system disables the motor if the current draw of the motor exceeds a fixed set point; and a proximity detection sensor being a strip of conducting material disposed adjacent to a perimeter of the desk surface and in electrical connection with an LC tank circuit, wherein the LC tank circuit is configured to exhibit a change in state when an object is in close proximity to the strip of conducting material and wherein the system disables the motor when the LC tank circuit exhibits the change in state.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/148,869, filed Oct. 1, 2018, now U.S. Pat. No. 10,617,201,which claims the benefits of U.S. Provisional Application Ser. No.62/566,913, filed Oct. 2, 2017, entitled “System and Method for ReducingInjury from Pinch Zones in Adjustable Height Work Surface Assemblies”and which is incorporated herein by this reference in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-R show a detailed circuit diagram of the system for reducinginjury from pinch zones in adjustable height work surface assemblies.The letters “I,” “O,” and “Q” have been deliberately omitted to avoidconfusion in the identification of the drawings.

FIG. 2a shows a two-leg embodiment of a height adjustable desk andillustrates placement of the system for reducing injury from pinch zonesin adjustable height work surface assemblies.

FIG. 2b shows a three-leg embodiment of a height adjustable desk andillustrates placement of the system for reducing injury from pinch zonesin adjustable height work surface assemblies.

FIG. 3 is a top view of a sensor strip for the system for reducinginjury from pinch zones in adjustable height work surface assemblies.

FIG. 4 is a cross-sectional view of the sensor strip for the system forreducing injury from pinch zones in adjustable height work surfaceassemblies.

FIG. 5 is a circuit diagram of a second embodiment for the system forreducing injury from pinch zones in adjustable height work surfaceassemblies.

FIG. 6 is a block diagram of the system for reducing injury from pinchzones in adjustable height work surface assemblies, in addition to theother components in a height-adjustable desk.

DETAILED DESCRIPTION OF THE DRAWINGS

Embodiments of a system for reducing injury in pinch zones in adjustableheight work surface assemblies are shown and described. The systemincludes a desk surface; at least one adjustable-height leg, saidadjustable height leg having an outer shell, a top casting forengagement with the desk surface and an actuator with a motor disposedwithin the outer shell for adjusting the height of the leg; a controllerfor the at least one adjustable-height leg, said controller having asystem for preventing pinch injuries during the operation of theadjustable height leg, said system comprising: a Hall-effect sensor inelectrical connection with an electrical input terminal of the motor,said H=all-effect sensor providing a signal to the system correspondingto a current draw of the motor and wherein the system is configured todisable the motor if the current draw of the motor exceeds a fixed setpoint; and a proximity detection sensor connected to the system, whereinsaid proximity detection sensor is a strip of conducting materialdisposed adjacent to a perimeter of the desk surface and in electricalconnection with an LC tank circuit, wherein said LC tank circuit isconfigured to exhibit a change in state when an object is in closeproximity to the strip of conducting material and wherein the system isconfigured to disable the motor when the LC tank circuit exhibits thechange in state. It should be appreciated that while one aspect of thesystem is to prevent fingers, hands, limbs, etc. from being pinchedduring the movement of a height-adjustable desktop, when such fingers,hands, limbs, etc. are caught between the moving desktop and some fixedobject, a further aspect of the system is to prevent damage to theheight adjustable desk and surrounding items by preventing movement ofthe desktop when furniture or other immovable items are in its path oftravel.

Reference is initially made to FIG. 6, which is a block diagram of thesystem for reducing injury from pinch zones in adjustable height worksurface assemblies, in addition to the other components in aheight-adjustable desk. The entire assembly 600 of a height-adjustabledesk equipped with the present system includes an adjustment switch 601.Adjustment switch 601 receives a user input 602, which takes the form ofan input to either raise or lower the height of the height adjustabledesktop. Electrical signals, indicating either raising or lowering thedesk are sent from the adjustment switch 601 to the motor controller603. The motor controller 603 communicates with the present system 604.As will be described in greater detail below, the system 604 determineswhether there is a collision, meaning that the height adjustable desktophas contacted an obstruction, or the proximity of an obstruction hasbeen detected. In either case, the system 604 will interrupt the motorcontroller's 603 signal to operate the height adjustable legs 605,notwithstanding the user input 602. Part of this determination by thesystem 604 is based on the input of sensors 606 into the system 604. Ifthere is no collision or the proximity of an obstruction detected, themotor controller 603 operates the height adjustable legs 605 either upor down depending on the user input 602.

FIGS. 1A-1R show a detailed circuit diagram for the system for reducinginjury from pinch zones in adjustable height work surface assemblies.FIGS. 1A, 1B and 1C show circuit components that monitor current loadson each of the three motors that, in conjunction with the actuators,allow for the vertical movement of the adjustable height legs. It shouldbe appreciated that the number of current load monitors corresponds tothe number of adjustable height legs, and by extension, therefore thenumber of motors in the assembly, each adjustable height leg operated byits own motor. In this example, three (3) legs are used, howeverassemblies having one (1), two (2) legs or assemblies having four (4) ormore legs are also possible and fall within the scope of thisdisclosure. The motors operate at a fixed speed, therefore, if the loadremains constant on the desktop then the motor current will remain thesame. If a collision occurs, then the controller will attempt to keepthe motor speed the same by modulating each motor's currentindividually. The collision detection system continually monitors thecurrent of each of the three motors, and is constantly looking for achange in the current demand over the measured average.

As can be seen in FIGS. 1A, 1B and 1C the current draw of each of thethree motors is measured using a Hall-effect current sensor fittedin-line with the motor +VE terminal. The Hall current sensor convertsthe measured current into a voltage which is linearly proportional tothe measured current. This voltage is then converted at a regular 10 mssampling interval using a 10-bit analogue-to-digital converter. Themotor current sense signals are sent to the microcontroller shown inFIG. 1D. The microcontroller performs the following software-definedfunctions. The digitally measured instantaneous current draw is fed intoan Infinite Impulse Response low pass filter, which gives a short-termaverage current consumption from the motor. The output from the filteris compared with the previous sample to provide a differential currentover time. The differential current is then fed into a windowedintegrator which sums the current differential over a longer time-frame.The system disables the motor function if the output from the integratorrises above a fixed set point. Thus, this portion of the circuit detectscollision of the moving desktop with obstructions by monitoring changesin motor current draw and disabling the motors when a collision isdetected.

In addition to detecting interference in the movement of the desktop bydetecting changes in motor current draw, the system also performsproximity detection based on a capacitance-to-frequency conversion. Thisproximity detection function allows for the motors in the legs to bedisabled when an obstruction, e.g. a piece of furniture or a human limbis present near the edge of the height adjustable desk. The proximitydetection is based on an LC tank resonator; which uses an inductor andcapacitor sensor to create an oscillation running at a fixed frequency,as shown in FIG. 1E. FIG. 1E shows four LC tank resonator sensors, aswould be applied to the four edges of a rectangular desk having heightadjustable functionality. It should be appreciated that additionalcapacitive sensors may be fitted externally to the system viaconnectors, for instance in cases where the geometry of the desktop issuch that more than four sensors are required to adequately surround theperimeter of the desktop. The sensor, which will be discussed in greaterdetail below, is designed such that its value changes with respect tothe proximity of an external object with a greater capacitance than thesensor itself, such as a hand or other body part.

The proximity of anything with a large capacitance compared to thecapacitive sensor will cause a change in the capacitance of the LC tankcircuit. This in turn will cause the frequency of the tank resonator todrop, the closer the obstruction is to the sensing strip. The change infrequency is measured by IC18 in FIG. 1E, and the result is sent to themicrocontroller in FIG. 1D.

The microcontroller in FIG. 1D performs the following software definedfunctions on, the frequency change signal received from the LC tankcircuit and IC18 in FIG. 1E, The incoming frequency measurement isfairly low noise, however, this signal can be affected by the proximityof external noise sources, such as computers and power supplies.Therefore, the input signal from the frequency converter is fed througha low pass filter. The absolute frequency of the sensor is not importantsince this will vary slightly over time due to temperature and humidity.The sensing system relies on being able to detect a short-term change inthe frequency. In order to do this the sensor is sampled over a longertime period, and an average value is then calculated. Any deviation fromthis long term average is then used to cause the system, to halt theoperation of the motors. In this way the proximity of an obstruction,either furniture or a human limb or part thereof, which causes afrequency change in the LC tank circuit results in stopping of the motorto prevent collision of the moving desktop with said obstruction.Additionally, the LC tank circuit frequency will increase if the sensoris disconnected from the system. In the case of sensor disconnection orfailure, the system also detects the accompanying change in frequencyand halts the operation of the motors. This prevents the heightadjustable desk from being operated if the system for preventing injuryfrom pinch zones is inoperable.

The circuit components shown in FIG. 1F provide a visual statusindication to the user, the indicators are controlled by themicrocontroller shown in FIG. 1D. This visual status indicator, e.g. anindicator light, can warn the user that the system has detected acollision or that a collision may be imminent. In some embodiments ofthe system, the visual status indicator may provide warning to the userof a collision or imminent collision, and the system may not stop themotors, instead relying on the visual status indicator's warning toallow the user to decide whether to continue operating theheight-adjustability function of the desk, and thereby manuallyover-riding the automatic stopping function of the system. The circuitcomponents shown in FIG. 1G link the system for reducing injury frompinch zones in adjustable height work surface assemblies via USB to ahost PC. The host PC can then be used to set-up the operatingparameters, and retrieve operating data from the module. The circuitcomponents shown in FIG. 1H are used to convert the higher voltagesignals from the motor controller into a voltage suitable for themicrocontroller in FIG. 1D. The circuit components of FIG. 1H performthis conversion on a per signal basis to protect the microcontrollerfrom the higher signal voltage that the controller supplies. The circuitcomponents shown in FIG. 1J generate an analogue signal between 0 and3.3V that is directly proportional to the current desk height. Themicrocontroller is able to read the digital height data that is sentfrom the motor controller and convert this into the analogue voltageusing a digital-to-analogue converter which is embedded in themicrocontroller in FIG. 1D. This part of the circuit provides a unitygain stable buffer.

The circuit components shown in FIG. 1K are a non-volatile flash memorydevice which is used by the microcontroller to store the moduleconfiguration parameters between power cycles. The circuit componentshown in FIG. 1L is the microcontroller programming connector. This isused to download the operating firmware to the microcontroller in thefactory. The circuit components shown in FIG. 1M are a linear regulatingpower supply that converts the motor controller 5V, direct current downto 3.3V, direct current suitable for the microcontroller. The circuitcomponents of FIG. 1M thereby generate a power source for themicrocontroller. This generated power source can provide enough currentto power the microcontroller and all the associated circuitry in thesystem. FIG. 1N shows a push button which can be used by the user toreset the module sensing algorithms as required. The components in FIG.1P provide an audio indication to the user that either a collision or aproximity detection event has occurred, similar to the visual indicatorpreviously described. In some embodiments of the system, the audioindicator may provide warning to the user of a collision or imminentcollision, and the system may not stop the motors, instead relying onthe audio indicator's warning to allow the user to decide whether tocontinue operating the height-adjustability function of the desk, andthereby manually over-riding the automatic stopping function of thesystem. Finally, FIG. 1R is the main electrical interface between thesystem for reducing injury from pinch zones in adjustable height worksurface assemblies, the adjustment switch and the main controller.

The following table gives a description of each component identified inthe circuit diagrams shown in FIGS. 1A-1R:

Designator Manufacturer Description C2, C3, C4, C6, C7, C8, C11, KemetCap 0402 100 nF 10% 16 V C14, C16, C17, C18, C19, C0402C104K4RACTU C22,C27, C28, C29, C33, C34, C35, C36, C37, C39, C41 C23 Kemet Cap 0402 10uF 20% 6.3 V C0402C106M9PACTU C5, C21, C40 AVX Cap 0805 4.7 uF 10% 16 V0805YC475KAT2A C1 Panasonic Cap eev_k16 4700 uF 20% 16 V EEVFK1C472MC42, C43, C44 Kemet Cap 0805 220 nF 5% 100 V C0805C224J1RACTU C20, C30Kemet, Cap 0805 1 uF 10% 50 V [NoParam] C0805C105K5RACTU C15 Kemet Cap0402 1 uF 10% 16 V C0402C105K4PAC7411 SK3 Hirose Connector; USBMicro- B,Reverse type, SMT; 5 Position; Right Angle IC16 Silicon Labs Single-ChipUSB to UART Bridge, 1024 Bytes EEPROM, −40 to 85 deg C., 28-pin QFN,Tube FB1 Murata Chip Ferrite Bead for Power Lines, 330 Ohm, 1500 mA, −55to 125 deg C., 2 × 1.25 × 1.05 mm SMD, Tape and Reel C25, C26, C31,C32Kemet CAP 33 pF 16 V ± 10% 0805 (2012 Metric) Thickness 1 mm SMD J3, J4,J5, J6, J7, J8 Molex Con 8-way MiniFit JR 39-30- 1080 J1, J2 CUI Inc Con7-way DIN SDS-70J J13 CNC Tech Con 10-way Header 1.27 mm 3220-10-0300-00J14 Molex Con 6-way Nano-Fit 105314- 1106 J9, J10, J11, J12 ZhejiangDeli Con 2-way ZJD AWB HY- 2AWB D17, D18 Avago Diode 0805 HSMC-C280 D2,D3, D4, D5, D6, D7, D8, AVX Diode 0402 5 V D9, D10, D11, D12, D13,GG040205100N2P D14, D16, D19, D20 D1 Microsemi Diode DO-214 BA 15 V 1 ALSM115JE3 D15 Nexperia Diode SOT143B 5.5 V PRTR5V0U2X L1, L2, L3, L4Abracon LLC Inductor 0805 0.9 mR 0.005 A AIML-0805-180K-T IC12, IC15,IC17 Allegro Allegro Microsystems Hall- Microsystems Effect CurrentACS723LLCTR-10AB-T soic_8 IC18 TI TI Capacitive Touch FDC2114 qfn_16 IC9Adesto Adesto Technologies Flash Technologies AT25SF161-SSHD sop_8 IC3Atmel Atmel ARM ATSAMD21J18A-A qfn_64 IC1, IC6 TI TI Quad bufferSN74LV125APWR tssop16 IC5, IC7, IC8 TI TI Buffer SN74LVC1G126 sot-23-5U1 Analog Analog Operation Amplifier AD8613AUJZ sot-23-5 IC2 TI TI QuadNAND SN74LVC00APWR tssop16 IC19 STMicro STMicro Voltage RegulatorLD1117DTTR dpak_3 B1 Soberton Electromagnetic Buzzer, 3.1 kHz, 83 dBAR31, R32 Vishay Res 0402 274R 1% CRCW0402274RFKED R34 Vishay Res 0402487R 1% CRCW0402487RFKED R16, R19, R21 Vishay Res 0402 511R 1%CRCW0402511RFKED R18, R20, R23, R50 Vishay Res 0402 1K00 1%CRCW04021K00FKED R12, R13, R15, R17, R22, Vishay Res 0402 4K64 1% R24,R25, R26, R28, R29, CRCW04024K64FKED R37, R38, R39, R40, R41, R51, R52,R68 R2, R3, R4, R5, R6, R7, R8, Vishay Res 0402 10K0 1% R9, R49CRCW040210K0FKED R14, R47 Vishay Res 0805 51R1 1% CRCW080551R1FKED R35Vishay Res 0805 1K00 1% CRCW08051K00FKED R1, R11, R46, R48, R58, VishayRes 0805 0 R -% R62, R66 CRCW08050000Z0EA R27 Vishay Res 0805 120 R 1%CRCW0805120RFKEA R30 Vishay Res 0805 200 R 1% CRCW0805200RFKEA SW1 TE TEConnectivity Connectivity FSM4JSMATR SMT TR1 Vishay MOSFET, N-CH, 30 V,1.2 A, Siliconix SOT-563

FIGS. 2a and 2b show height adjustable desks and illustrates placementof the system for reducing injury from pinch zones in adjustable heightwork surface assemblies. FIG. 2a shows an embodiment of a heightadjustable desk with two legs, while FIG. 2b shows an embodiment of aheight adjustable desk with three legs. Like numerals will be used toidentify like features common to both FIGS. 2a and 2b . Thus, FIGS. 2aand 2b show the height adjustable desk assembly 200 with heightadjustable legs 201 and desktop surface 202. Also shown is the edge 203of desktop surface 202. Embodiments of the present system may bedisposed on the edge 203 or they may be disposed on the underside of thedesktop surface 202 adjacent to the edge 203. In some embodiments, thepresent system will not be provided at the front edge 204 of the desktopsurface 202, while in other embodiments, the system will be provided atedge 204. The present system may be provided at all edges of the desktopsurface 202 or only at selected edges, depending on the needs of theuser.

FIGS. 3 and 4 show an embodiment for a sensor strip for the system forreducing injury from pinch zones in adjustable height work surfaceassemblies. FIG. 3 shows a top view of the sensor strip 300, and FIG. 4shows a cross-sectional view of the sensor strip 300. As can be seen inFIG. 3, the sensor strip 300 has a long, narrow body 301 with aconnector 302 disposed at one end thereof. By way of example, andwithout limitation, the sensor strip 300 may be 800 mm long and 12 mmwide. One of ordinary skill in the art will readily appreciate that thedimensions of the sensor strip may vary depending on the user'sparticular application. For example, sensor strips both longer andshorter than the dimensions recited above may be necessary to fit auser's desk. The sensor strip may be attached the desk by any meansknown in the art, including adhesive or mechanical fasteners.

FIG. 4 shows a cross-sectional view of the sensor strip 300. The bottomlayer 401 of the sensor strip 300 consists of an FR4 substrate. Thisbottom layer 401 is a flexible, insulating layer that forms the base ofthe sensor strip 300. Disposed on top of the bottom layer 401 is theconducting layer 402. The conducting layer 402 performs the sensingfunction of the strip, it conducts the electrical signals produced bythe circuit described above, which are effected by the proximity ofobstructions and thereby sensed by the above-described circuit. Theconducting layer 402 may be made of any acceptable conducting material,including by way of example and without limitation, copper, aluminum orgold. A connector 404 is electrically connected by solder 405 to theconducting layer 402. A wire 406, electrically connected to theconnector 404, joins the sensor strip 300 to the circuit described inFIG. 1A-R. The topmost layer of the sensor strip 300 is the solderresist 403. The solder resist 403 covers and insulates the conductinglayer 402. An aperture in the solder resist 403 allows the connector 404to be soldered to the conducting later 402. It should be appreciatedthat the sensor strip 300 is very low profile, so as not to obstruct theuser's movement around a desk. Moreover, the sensor strip 300 isflexible, to allow it to conform to a variety desk underside surfaces.Additionally, the sensor strip is fabricated such that it can be cut tothe required length. It should be appreciated that different sensormaterials, other than what has been described with respect to FIGS. 3and 4 can be used. Several suitable materials have been identified forthe sensor material, including, aluminum sheets, copper tape, solidcopper wire, braided copper wire, and aluminum tape conductive, flexibleplastic sheets coated with indium tin oxide were also found to be anacceptable sensor material. All of these materials could be used as thesensor strip in place of the sensor described in FIGS. 3 and 4.

FIG. 5 is a circuit diagram of an alternate embodiment for the systemfor reducing injury from pinch zones in adjustable height work surfaceassemblies. The circuit 500 for the system consists of three majorparts. The first part is the microcontroller 501 and battery pack 502.The microcontroller 501 may be an Arduino Uno R3 microcontroller board.Battery pack 502 may be provided to provide the required operatingvoltage for the microcontroller 501. One of ordinary skill in the artwill appreciate that any power supply that meets the power inputrequirements of microcontroller 501 could be used, inclusive ofbatteries or standard electrical mains power either transformed into asuitable voltage or untransformed. Additionally, the microcontroller mayalso be powered by the same power source that operates the adjustableheight legs.

Also shown in FIG. 5 is the sensor circuit 503, which consists of sensor504 and sensor circuit resistors 505. Sensor circuit resistors 505 mayconsisting of 30 MΩ of resistance, and may be provided in any form knownin the art. The amount of resistance chosen for the sensor circuitresistors 505 effects the performance of the overall system. Differentresistance values from 1 MΩ to 40 MΩ may be used and the amount neededvaries based upon the amount of sensitivity desired and the amount ofsensor material used. Generally, the higher the resistance of sensorcircuit resistors 105, the higher the sensitivity of the system.However, if higher resistance values are used for sensor circuitresistors 505, this slows down the detection circuit so to maintain areal-time reaction the speed and sensitivity must be balanced.

Also part of the sensor circuit 503 is the sensor 504. This is thematerial that senses the conductive object in its proximity and orresponds to being touched by the user. It must be conductive and it mustbe capable of having an electrical connection made to it, either viasoldering or a physical connector. It also must have sufficient surfacearea to detect the proximity of an obstruction in the path of thedesktop. Several suitable materials have been identified for the sensormaterial, including aluminum sheets, copper tape, solid copper wire,braided copper wire, and aluminum tape. Conductive, flexible plasticsheets coated with indium tin oxide were also found to be an acceptablesensor material. As an example, and without limitation, aluminum tapemay be used for the sensor material. The aluminum tape was applied in acontinuous run of 138″ or 3.5 meters long, thereby applying the sensorto the perimeter of the desk except for the front edge and was found tofunction acceptably as the sensor. The sensor may have an adhesive onone side or it may be attached to the desk with mechanical connections.

Also shown in FIG. 5 is the relay 506. The relay 506 may be a 5V relayand is controlled by microcontroller 501. The relay 506 interrupts thesignal from control switch 507 to the input 508 of the adjustable heightleg, upon receiving a signal from the microcontroller that the sensorhas detected an obstruction in the path of the desktop. It should beappreciated that the relay will interrupt signals from any heightadjustable leg system that the user implements on a desk. Thus,connections on the housing for the detection system may be provided thataccommodate different manufacturers' connection schemes, including byway of example and without limitation, 7-pin serial connectors and RJ45jacks.

The microcontroller 501 is programmed with code to perform thecalculations necessary to complete the sensing functions. It wasdetermined that there are several parameters in the code that allow thesystem to function correctly. The basic program simply measures the timeit takes to complete the sensor circuit in milliseconds. If the valuewas greater than a defined value an obstruction was detected. To addressthe highly variable sensor data, a moving average with a parameter forsample size may be employed. This takes 10-1000 sensor readings andaverages them together to smooth out the spikes in the sensor data. Thisparameter presents a trade-off between speed and sensitivity. A lowsample size of 10 preserves speed of calculation but allows variabilityin the sensor data. Higher values like 1000 slow down the data to about1 reading a second and produces almost completely uniform data that ishighly resistant to change. Additionally, the program implements a 1second delay after the relay trips to prevent the relay from tripping onand off and making it was difficult to determine what stimuli had causedthe relay to trip.

Another problem that the programming addresses is that variability ofinstallation types that are encountered in the field. The present systemwill be installed in a wide variety of different environments and thesensor values could be in range of 250±20 or 15,000±1,000 just basedupon the office environment. Setting a static threshold value fortriggering the relay will not work in such a variable environment.Therefore, the trigger threshold is set to be a percentage of the sensorvalue to accommodate low and high baseline sensor readings. The programtakes a sensor reading computed from the running average of 25 readings,it divides by 100 to get a number equal to 1% of the sensor reading.Then this number is multiplied by 15 to get 15% of the sensor readingthis is then added to the sensor value. Next the program compares thenext sensor value to determine if it is larger than the previous sensorvalue+15% if it is, the relay is tripped then waits one second andstarts over. If not, it stores the current value as the previous valueand starts over.

Other additional problems are solved by the programming. Occasionally,electromagnetic interference from other sources will cause the sensorvalues to be greatly reduced, which causes associated calculations tofail. To solve this problem a parameter arbitrarily adds 1000 to all ofthe sensor values to prevent the calculations from failing.Additionally, to solve the problem of the relay triggering on startupbecause the program uses the previous value of 0 in the calculations, anarbitrary high value of 5000 is set as the first ‘previous value’ beforeit is replaced with the sensor value from the first cycle of the programat the end of the first cycle.

It will be appreciated by those of ordinary skill in the art that, whilethe forgoing disclosure has been set forth in connection with particularembodiments and examples, the disclosure is not intended to benecessarily so limited, and that numerous other embodiments, examples,uses, modifications and departures from the embodiments, examples anduses described herein are intended to be encompassed by the claimsattached hereto Various features of the disclosure are set forth in thefollowing claims.

1. An assembly comprising: a desk surface; at least oneadjustable-height leg, said adjustable height leg having an outer shell,a top casting for engagement with the desk surface and an actuator witha motor disposed within the outer shell for adjusting the height of theleg; a controller electrically connected to the at least oneadjustable-height leg, said controller having an adjustment switch forreceiving a user input to raise or lower the adjustable-height leg, saidcontroller further having a system for preventing pinch injuries duringthe operation of the adjustable height leg, said system comprising: aHall-effect sensor in electrical connection with an electrical inputterminal of the motor, said Hall-effect sensor providing a signal to thesystem corresponding to a current draw of the motor and wherein thesystem is configured to activate an indicator if the current draw of themotor exceeds a fixed set point; a proximity detection sensor connectedto the system, wherein said proximity detection sensor is a strip ofconducting material disposed adjacent to a perimeter of the desk surfaceand in electrical connection with an LC tank circuit, said LC tankcircuit in electrical connection with the controller, wherein said LCtank circuit is configured to exhibit a change in state when an objectis in close proximity to the strip of conducting material and whereinthe system is configured to activate the indicator when the LC tankcircuit exhibits the change in state, and wherein pinch injuries areprevented by the system activating the indicator to alert a user that acollision or a proximity detection event has occurred or may imminentlyoccur.
 2. The assembly of claim 1, wherein the system for preventingpinch injuries is powered by electrical power from the controller. 3.The assembly of claim 1, wherein the at least one adjustable-height legis provided with a foot casting and is free-standing.
 4. The assembly ofclaim 1, wherein three adjustable-height legs are included in theassembly.
 5. The assembly of claim 1, wherein the indicator is a visualindicator.
 6. The assembly of claim 1, wherein the indicator is an audioindicator.
 7. The assembly of claim 1, wherein the system for preventingpinch injuries is battery powered.
 8. An assembly comprising: a desksurface; at least one adjustable-height leg, said adjustable height leghaving an outer shell, a top casting for engagement with the desksurface and an actuator with a motor disposed within the outer shell foradjusting the height of the leg; a controller electrically connected tothe at least one adjustable-height leg, said controller having anadjustment switch for receiving a user input to raise or lower theadjustable-height leg, said controller further having a system forpreventing pinch injuries during the operation of the adjustable heightleg, said system comprising: a proximity detection sensor connected tothe system, wherein said proximity detection sensor is a strip ofconducting material disposed adjacent to a perimeter of the desk surfaceand in electrical connection with an LC tank circuit, said LC tankcircuit in electrical connection with the controller, wherein said LCtank circuit is configured to exhibit a change in state when an objectis in close proximity to the strip of conducting material and whereinthe system is configured to disable the motor when the LC tank circuitexhibits the change in state, and wherein pinch injuries are preventedby disabling the motor notwithstanding motor activation input from auser.
 9. The assembly of claim 8, wherein the change in state of the LCtank circuit is a change in capacitance.
 10. The assembly of claim 8,wherein the change in state of the LC tank circuit is a change infrequency.
 11. The assembly of claim 8, the LC tank circuit's frequencychanges when the proximity detection sensor is disconnected and thecontroller disables the motor in response to this frequency change. 12.The assembly of claim 8, wherein the proximity detection sensor isformed from a material selected from the group comprising aluminumsheets, copper tape, solid copper wire, braided copper wire, aluminumtape and plastic sheets coated with indium tin oxide.
 13. The assemblyof claim 8, wherein the proximity detection sensor is provided at alledges of the desk surface.
 14. The assembly of claim 8, wherein theproximity detection sensor is provided at selected edges of the desksurface.
 15. The assembly of claim 8, wherein the system for preventingpinch injuries is powered by electrical power from the controller. 16.An assembly comprising: a desk surface; at least one adjustable-heightleg, said adjustable height leg having an outer shell, a top casting forengagement with the desk surface and an actuator with a motor disposedwithin the outer shell for adjusting the height of the leg; a controllerelectrically connected to the at least one adjustable-height leg, saidcontroller having an adjustment switch for receiving a user input toraise or lower the adjustable-height leg, said controller further havinga system for preventing pinch injuries during the operation of theadjustable height leg, said system comprising: a Hall-effect sensor inelectrical connection with an electrical input terminal of the motor,said Hall-effect sensor providing a signal to the system correspondingto a current draw of the motor and wherein the system is configured todisable the motor if the current draw of the motor exceeds a fixed setpoint; and wherein pinch injuries are prevented by disabling the motornotwithstanding motor activation input from a user.
 17. The assembly ofclaim 16, wherein the system for preventing pinch injuries is powered byelectrical power from the controller.
 18. The assembly of claim 16,wherein the at least one adjustable-height leg is provided with a footcasting and is free-standing.
 19. The assembly of claim 16, whereinthree adjustable-height legs are included in the assembly.
 20. Theassembly of claim 16, wherein the system for preventing pinch injuriesis battery powered.